Excess-electric-current indicator.



J. STONE.

- EXCESS ELECTRIC CURRENT INDICATOR.

APPLIUATION' FILED P313. 9, 1912.-

Patented Juli 28, 1914.

IN VENTOR.

. Indicators, of which UNITED STATES PATENT oFFIcE.

JOHN STONE, 0F PITTSQURGH, PENNSYLVANIA, ASSIGNOR TO EXCESS INDICATOR vC01\I[PA1|' Y,.A CORPORATION OF PENNSYLVANIA.

EXCESS-ELECTRIC-CURRENT INDICATOR.

Specification of Letters Patent. Pgffignfied July 28, 1914,, Application filed February 9, 1912. Serial No. 676,550.

. State of Pennsylvania, have made a new and useful Invention in Excess-Electric-Current the following is a specification. L

This invention relates to excess electric current indicators, that is, to that class of devices which normally remain. inactive so long as the amount of current used does not exceed a' predetermined amount, but which operate upon excess current demand. For

example, suppose a service company contracts with a consumer to furnish enough current to light five lamps for a given amount. So long as five lamps or less are lighted the device will remain inactive;

should a greater number of lamps be put on the line, the circuit would be broken and closed in sufficiently rapid succession to make the lamps flicker. Therefore, it will,be necessary for the consumer to turn off the extra lamps in order to restore the brilliancy of the lamps for the illumination of which he is paying. It sometimes happens, however, that the consumer will put a relatively heavy load on the line, such as a sad iron, or other heater, which in some cases will demand more than double the amount of current for which the consumer agrees to pay. Even though the circuit is broken and reestablished with such frequency as to prevent the iron or the like.

ample, when an extra lamp is switched on,

the circuit will be interrupted so as to make the lamps flicker In the event that the current demand he further in excess ofthat for which the consumer is paying, a resist- 1 not been paid.

conductor 12. 'nect'ed to the contact 14 and to conductor 85 ance will be cut in the circuit thereby reducing the strength of the current, whereby the device demanding the greatly excessive current will not he serviceable and the larnps will be dimmed sothat the device using excess current must be removed be-' fore the brilliancy of the normally operated lamps can be restored. In thisway, the central station will be protected 'againstthe consumption of current for which they have In the drawings, the figure is a diagrammatical view of the wiring and elements illustrative of my invention.

Referring now to the drawings by numerals of reference: 1' and 2 are connectors for. the incoming current, and 3 and 4 are connectors for conductors for the load In the drawings I have illustrated a series coil 5, a shunt coil 6, a circuit breaker 7, a

resistance 8, and a spring-controlled arma- 7o ture 9 with appropriate connections, and I shall now proceed to describe how these connections may be made. a

A conductor 10 leads from 1 to 3 but between its respective ends is the series coil 5. A conductor 12 leads from 2 to the-contact 13 on the circuit breaker 7, said contact 13 being insulated from the contact 14 by the bar 15. The contact 13 (when the circuit is closed) may make contact with contact 13 which is. connected to connector 4 byco-nductor 12. The spring-controlled armature 9 is connected to the contact 14: by a The shunt'o'il 6 is con- 12. The resistance 8 is connectedjto the conductor 12 and to normally open contact 8. I

10 is ajc'ontact tapped into the conductor 10 while10 is a stop.

Now, suppose all the parts are properly arranged upon a suitable base and properly installed: Current may enter through the conductor 10 series coil 5 past 3 and out on the line. The return may be through 4, 12 12 and out through 2. -Should sli ht ovcr-' load current iiow through coil 5 Fsaid coil being really a magnet), the armature 9 will be pulled down so as to makecontact' with 10. Current will flow through 1, 9, 12", 1e, 14, shunt coil 6, 12 to 13*, 13 to 2, as well as through 1 to 5 and 3. lhe shunt coil 6 1 will be energized and acting as a solenoid will actuate the circuit-breaker 7 to interrupt the current. Because the shunt coil will not be sufficiently energized, it will let the circuit-breaker drop back and close the circuit. This will be done with suflicient rapidity to cause-the lamps to fiicker. As soon as the cause of the overflow current is removed (usually by cutting out a lamp), the series coil 5 will be deenergized, the contact between the armature 9 and contact 10 will be broken and the whole normal conditions reestablished. Suppose there is (EXCEL sive overload current demanded upon the line, the shunt coil 6 will pull up on the breaker 7 so as to substantially open the main line circuit, the magnetism of the coil 6 being sufiicient'to hold the contact 14: in contact with 8 so the resistance is cut in across the line and the current passes through both the resistance 8 and the coil 6, the resistance being such that only a small amount of current can get past the connectors 3 and 4. As soon as the excessively heavy demand ceases, the coil 6 will cease to be a magnet sufliciently strong to hold the breaker 7, and the resistance will be cut out.- If the normal demand again prevails, the circuit will be -reestablished and the device will remain inactive until again disturbed by an overload demand. The tension I of the spring armature 9 may be adjusted to respond to a given pull by the worm gear 15 to be manually operated.

The variable resistance 16 may be adjusted by the threaded rod 17 and contact 18 in any well known manner.

From the foregoing, it will be apparent that when on account of a slight overload the armature 9 closes the circuit of the magnet 6, the latter is in shunt with the line and receives full line potential, whereas as soon as the said magnet is energized it automatically intermittently interrupts the circuit and: upon a'further increase overload it changes its own connection by contact 14:, leaving contact 14 and engaging contact 8. When this occurs the magnet 6 is no 7 longer in shunt with the line but in series therewith, consequently the amount of current flowing through it depends upon the resistance in series with the line, which includes the resistance 8 and the resistance of the load. If the load is large, its resistance is low, and magnet 6 will receive enough current to hold it up.

While I have specifically described my invention in order to enable those skilled in the art to fully understand and construct one form thereof, I would have it understood that I do not limit myself to the de- -matically changing the connections of said electro-responsive mechanism to cause it to keep the main line substantially open during a greater excess demand.

2. The combination of a lamp circuit, electro-responsive mechanism associated therewith for intermittently opening and closing the lamp circuit when a predetermined excess demand is imposed on the circuit, a resistance and means for automatically changing the connections of said elecarc-responsive mechanism when a greater load is imposed on the circuit to cause it to include said resistance in series with the lamps to reduce the strength of the-current flowing through the circuit and there "im the lamps.

3. In an excess electric current indicator, a device comprising incoming and outgoing circuit terminals, a magnet, an armature, a switch operated thereby, a second switch operated by said magnet and closed by a predetermined movement of the armature in a direction to open the first switch, connections for including the magnet, terminals and second named switch in series, and a resistance connected between one of the terminals and the second switch.

4. A main electric circuit, av magnet in the main circuitcolnprising a series coil, a circuit in shunt with the line, a magnet in the shunt circuit, a contact, an armature res onsive to the series coil magnet to engage the contact to close the shunt circuit and energize the magnet therein, a switch responsive to the shunt coil, a resistance conhas operated the first mentioned switch to open the shunt circuit.

The combination of a mainline, electroresponsive mechanism associated therewith for intermittently opening and closing the main line circuit upon a predetermined eX- cess current demand on the line and means for automatically changing the electrical In testimony whereof, I have hereunto connections of said electro-responsive mechsubscribed my name this 3rd day of Februanism to cause it to cease intermittently my; 1912.

opening and closing the circuit and to re- JOHN STONE.

'5 duce the strength of the current in the main Witnesses:

line during a greater excess demand on the WM. L. LOEB,

B. F. FUNK.

- main line.

Copies of thil patent may be obtained for five cent: each, by addressing the Commissioner of Patents.

I Washington, D. 0." 

